I go either way depending on my mood, but 90% of the time I don't mind sitting in a bar area of a restaurant with a Business Week or Economist magazine and enjoying a meal. I rarely go somewhere where I am forced to sit at a table alone for dinner.
The worst part for me is that it feels like I always get stuck beside the one person who is chewing with his mouth open. It's poor form and rude to others around and it disrupts my enjoyment of the evening.
I find that chatty bartenders and waitstaff are generally very enjoyable and make the trip that much more interesting.
I live alone, and go out for lunch everyday alone when I'm home. Not a big deal for me.